Former Gladstone Police Sgt. Lynn Benton talks by video with his attorney, Lisa Ludwig, before he is arraigned in Clackamas County Circuit Court.Doug Beghtel/The Oregonian

The plot to kill Deborah Higbee Benton was hatched more than a year before the beautician was found dead in her Gladstone shop and several months before she married the former cop accused of killing her.

Those details surfaced on a whirlwind Thursday when Higbee Benton's husband, former Gladstone police Sgt. Lynn Benton, was formally charged with murder and a third suspect was arrested for his role in the alleged conspiracy to kill Higbee Benton.

Jason Jay Jaynes, 32, was arrested Thursday during a traffic stop and taken into custody on accusations of attempted aggravated murder and conspiracy. He will be arraigned Friday in Clackamas County Circuit Court.

Jaynes is the son of Susan Ellen Campbell, also accused of participating in the May 2011 slaying.

Higbee Benton, 54, was found in her beauty salon, the victim of beating, strangulation and a gunshot wound in the back.

Jaynes and Campbell agreed to help Benton kill his wife in a conspiracy that may have started as early as January 2010 and were involved other attempts to kill Higbee Benton, according to an indictment made public Thursday.

Benton tried to kill his wife on Feb. 6, 2011, according to the indictment that provided no specific details about the event.

Jaynes and Campbell were to be paid for their participation, the indictment said.

Campbell told investigators Benton was going to pay her $2,000 to commit the murder, Oregon City police Detective Brad Edwards, the lead investigator testified at a hearing last year.

Campbell, 54, a longtime friend of Benton, is expected to enter a guilty plea Friday as part of an agreement that calls for her to testify against Benton.

Investigators believe tensions in Benton and Higbee Benton's relationship arose in part over Benton's gender reassignment.Benton, formerly Lynne Irene Benton, underwent a female-to-male sex change operation in 2009, something Higbee Benton originally supported, then opposed, Edwards said. That led Benton to move out of their home a month before the killing.

In an interview, Benton admitted to physically abusing Higbee Benton, one time choking her and pinning her against the wall, Edwards said.

Benton, 50, appeared in court via closed-circuit television. He told the judge he could hear the proceedings but said nothing else during the brief hearing.

Benton is being held without bail at the Clackamas County jail.

Because Benton is a former police officer, he is being held in "administrative segregation," separate from other inmates, said Lt. Lee Eby, a jail commander.

Gladstone fired Benton last year for reasons unrelated to the murder.

Benton, who was working as a Greyhound bus driver, was arrested Wednesday in Portland when he arrived at work.